Bergamottin, a natural furanocoumarin obtained from grapefruit juice induces chemosensitization and apoptosis through the inhibition of STAT3 signaling pathway in tumor cells

Potential function of oxymatrine as a novel suppressor of epithelial-to-mesenchymal transition in lung tumor cells

AIMS

Tumor cells metastasis as well as proliferation are important factors that can substantially determines the prognosis of cancer. In particular, epithelial-mesenchymal transition (EMT) is key phenomena which can cause tumor cell transition into other organs by promoting the disruption of the cell-cell junctions. Because oxymatrine (OMT) have been reported to attenuate the tumor growth, we investigated whether OMT can down-regulate EMT process in tumor cells. We also focused on transforming growth factor-β (TGF-β)-induced EMT process because EMT process can be significantly induced by this growth factor.

MAIN METHODS

The cell viability was measured by MTT and real time cell analysis (RTCA) assay. The expression levels of various proteins involved in the regulation of EMT and Akt/mTOR/PI3K signaling pathway were evaluated by Western blot analysis. mRNA levels of several important EMT markers were analyzed by reverse transcription polymerase chain reaction (RT-PCR). The effects of OMT on the cellular invasion and migration were evaluated by RTCA, wound healing assay, and boyden chamber assays.

KEY FINDINGS

OMT suppressed the expression of both constitutive and TGF-β-induced mesenchymal markers, such as fibronectin, vimentin, MMP-9, MMP-2, N-cadherin, Twist, and Snail, but induced the levels of epithelial markers. Moreover, OMT down-regulated oncogenic PI3K/Akt/mTOR pathways which lead to a significant attenuation of invasive and migratory potential of lung cancer cells.

SIGNIFICANCE

Overall, our study established a novel anti-metastatic role of OMT against human lung cancer cells.

Tris(dibenzylideneacetone)dipalladium(0) (Tris DBA) Abrogates Tumor Progression in Hepatocellular Carcinoma and Multiple Myeloma Preclinical Models by Regulating the STAT3 Signaling Pathway

Simple Summary

STAT3 is a major oncogenic transcription factor that is constitutively activated in many types of human cancers, including hepatocellular carcinoma (HCC) and multiple myeloma (MM). Many STAT3 inhibitors have gained momentum in clinical trials towards the treatment of various cancers. In the present study, we have investigated the STAT3 inhibitory efficacy of Tris DBA, a palladium-based compound, in HCC and MM cancer cells and preclinical cancer models. Tris(dibenzylideneacetone)dipalladium(0) (Tris DBA) abrogated the STAT3 signaling pathway in both models by elevating the expression of SHP2. Functionally, Tris DBA inhibited cell proliferation, migration, invasion, and regressed tumor metastasis. Although many studies propose Tris DBA as a modulator of MAPK, Akt, phospho-S6 kinase, and N-myristoyltransferase-1, we have comprehensively demonstrated for the first time that Tris DBA is an inhibitor of STAT3 signaling in preclinical cancer models. These results support the consideration of Tris DBA in clinical trials in translational relevance.

Abstract

STAT3 is an oncogenic transcription factor that controls the expression of genes associated with oncogenesis and malignant progression. Persistent activation of STAT3 is observed in human malignancies, including hepatocellular carcinoma (HCC) and multiple myeloma (MM). Here, we have investigated the action of Tris(dibenzylideneacetone) dipalladium 0 (Tris DBA) on STAT3 signaling in HCC and MM cells. Tris DBA decreased cell viability, increased apoptosis, and inhibited IL-6 induced/constitutive activation of STAT3, JAK1, JAK2, and Src in HCC and MM cells. Tris DBA downmodulated the nuclear translocation of STAT3 and reduced its DNA binding ability. It upregulated the expression of SHP2 (protein and mRNA) to induce STAT3 dephosphorylation, and the inhibition of SHP2 reversed this effect. Tris DBA downregulated the expression of STAT3-driven genes, suppressed cell migration/invasion. Tris DBA significantly inhibited tumor growth in xenograft MM and orthotopic HCC preclinical mice models with a reduction in the expression of various prosurvival biomarkers in MM tumor tissues without displaying significant toxicity. Overall, Tris DBA functions as a good inhibitor of STAT3 signaling in preclinical HCC and MM models.

Targeting Cancer Stem Cells by Dietary Agents: An Important Therapeutic Strategy against Human Malignancies

As a multifactorial disease, treatment of cancer depends on understanding unique mechanisms involved in its progression. The cancer stem cells (CSCs) are responsible for tumor stemness and by enhancing colony formation, proliferation as well as metastasis, and these cells can also mediate resistance to therapy. Furthermore, the presence of CSCs leads to cancer recurrence and therefore their complete eradication can have immense therapeutic benefits. The present review focuses on targeting CSCs by natural products in cancer therapy. The growth and colony formation capacities of CSCs have been reported can be attenuated by the dietary agents. These compounds can induce apoptosis in CSCs and reduce tumor migration and invasion via EMT inhibition. A variety of molecular pathways including STAT3, Wnt/β-catenin, Sonic Hedgehog, Gli1 and NF-κB undergo down-regulation by dietary agents in suppressing CSC features. Upon exposure to natural agents, a significant decrease occurs in levels of CSC markers including CD44, CD133, ALDH1, Oct4 and Nanog to impair cancer stemness. Furthermore, CSC suppression by dietary agents can enhance sensitivity of tumors to chemotherapy and radiotherapy. In addition to in vitro studies, as well as experiments on the different preclinical models have shown capacity of natural products in suppressing cancer stemness. Furthermore, use of nanostructures for improving therapeutic impact of dietary agents is recommended to rapidly translate preclinical findings for clinical use.

Circular RNAs in cell cycle regulation: Mechanisms to clinical significance

Circular RNAs (circRNAs), a type of non‐coding RNA, are single‐stranded circularized molecules characterized by high abundance, evolutionary conservation and cell development‐ and tissue‐specific expression. A large body of studies has found that circRNAs exert a wide variety of functions in diverse biological processes, including cell cycle. The cell cycle is controlled by the coordinated activation and deactivation of cell cycle regulators. CircRNAs exert mutifunctional roles by regulating gene expression via various mechanisms. However, the functional relevance of circRNAs and cell cycle regulation largely remains to be elucidated. Herein, we briefly describe the biogenesis and mechanistic models of circRNAs and summarize their functions and mechanisms in the regulation of critical cell cycle modulators, including cyclins, cyclin‐dependent kinases and cyclin‐dependent kinase inhibitors. Moreover, we highlight the participation of circRNAs in cell cycle‐related signalling pathways and the clinical value of circRNAs as promising biomarkers or therapeutic targets in diseases related to cell cycle disorder.

Pyrimidine-2,4-dione targets STAT3 signaling pathway to induce cytotoxicity in hepatocellular carcinoma cells

Signal transducer and activator of transcription 3 (STAT3) is a tumorigenic transcription factor that is persistently activated in various human cancers including hepatocellular carcinoma (HCC). Therefore, STAT3 is considered as a prominent target to counteract the uncontrolled proliferation of cancer cells. In the present report, pyrimidine-2,4-diones (N-methyluracil derivatives) (MNK1-MNK14) were synthesized in an ionic liquid (BMIm PF₆) medium employing a ligand-free Suzuki-Miyaura cross-coupling process. Among the 14 derivatives, compound MNK8 showed good cytotoxicity towards both the tested cell lines and did not display a toxic effect against normal hepatocytes (LO2). MNK8 significantly increased the Sub-G1 cell count in both cell lines and the cytotoxic effect of MNK8 was found to be mediated through the suppression of constitutive phosphorylation of STAT3^Y705. It also decreased the DNA interaction ability of nuclear STAT3 in HCC cells. MNK8 downregulated the levels of apoptosis-related proteins (such as Bcl-2, cyclin D1, survivin) and increased cleaved caspase-3 inferring the apoptogenic effect of MNK8. It also reduced the CXCL12-triggered cell migration and invasion in in vitro assay systems. Overall, MNK8 has been demonstrated as a new inhibitor of STAT3 signaling cascade in HCC cells.

Bergamottin a CYP3A inhibitor found in grapefruit juice inhibits prostate cancer cell growth by downregulating androgen receptor signaling and promoting G0/G1 cell cycle block and apoptosis

Prostate cancer is the second leading cause of cancer related death in American men. Several therapies have been developed to treat advanced prostate cancer, but these therapies often have severe side effects. To improve the outcome with fewer side effects we focused on the furanocoumarin bergamottin, a natural product found in grapefruit juice and a potent CYP3A inhibitor. Our recent studies have shown that CYP3A5 inhibition can block androgen receptor (AR) signaling, critical for prostate cancer growth. We observed that bergamottin reduces prostate cancer (PC) cell growth by decreasing both total and nuclear AR (AR activation) reducing downstream AR signaling. Bergamottin’s role in reducing AR activation was confirmed by confocal microscopy studies and reduction in prostate specific antigen (PSA) levels, which is a marker for prostate cancer. Further studies revealed that bergamottin promotes cell cycle block and accumulates G0/G1 cells. The cell cycle block was accompanied with reduction in cyclin D, cyclin B, CDK4, P-cdc2 (Y15) and P-wee1 (S642). We also observed that bergamottin triggers apoptosis in prostate cancer cell lines as evident by TUNEL staining and PARP cleavage. Our data suggests that bergamottin may suppress prostate cancer growth, especially in African American (AA) patients carrying wild type CYP3A5 often presenting aggressive disease.

Crocetin imparts antiproliferative activity via inhibiting STAT3 signaling in hepatocellular carcinoma

STAT3 is a key oncogenic transcription factor, often overactivated in several human cancers including hepatocellular carcinoma (HCC). STAT3 modulates the expression of genes that are connected with cell proliferation, antiapoptosis, metastasis, angiogenesis, and immune evasion in tumor cells. In this study, we investigated the effect of crocetin on the growth of HCC cells and dissected its underlying molecular mechanism in imparting a cytotoxic effect. Crocetin suppressed proliferation, promoted apoptosis, and counteracted the invasive capacity of HCC cells. Besides, crocetin downregulated the constitutive/inducible STAT3 activation (STAT3^Y705 ), nuclear accumulation of STAT3 along with suppression of its DNA binding activity in HCC cells with no effect on STAT5 activation. Crocetin suppressed the activity of upstream kinases such as Src, JAK1, and JAK2. Sodium pervanadate treatment terminated the crocetin-propelled STAT3 inhibition suggesting the involvement of tyrosine phosphatases. Crocetin increased the expression of SHP-1 and siRNA-mediated SHP-1 silencing resulted in the negation of crocetin-driven STAT3 inhibition. Further investigation revealed that crocetin treatment inhibited the expression of STAT3 regulated genes (Bcl-2, Bcl-xL, cyclin D1, survivin, VEGF, COX-2, and MMP-9). Taken together, this report presents crocetin as a novel abrogator of the STAT3 pathway in HCC cell lines.

Long non-coding RNAs as new players in bladder cancer: Lessons from pre-clinical and clinical studies

The clinical management of bladder cancer (BC) has become an increasing challenge due to high incidence rate of BC, malignant behavior of cancer cells and drug resistance. The non-coding RNAs are considered as key factors involved in BC progression. The long non-coding RNAs (lncRNAs) are RNA molecules and do not encode proteins. They have more than 200 nucleotides in length and affect gene expression at epigenetic, transcriptional and post-transcriptional phases. The lncRNAs demonstrate abnormal expression in BC cells and tissues. The present aims to identifying lncRNAs with tumor-suppressor and tumor-promoting roles, and evaluating their roles as regulatory of growth and migration. Apoptosis, glycolysis and EMT are tightly regulated by lncRNAs in BC. Response of BC cells to cisplatin, doxorubicin and gemcitabine chemotherapy is modulated by lncRNAs. LncRNAs regulate immune cell infiltration in tumor microenvironment and affect response of BC cells to immunotherapy. Besides, lncRNAs are able to regulate microRNAs, STAT3, Wnt, PTEN and PI3K/Akt pathways in affecting both proliferation and migration of BC cells. Noteworthy, anti-tumor compounds and genetic tools such as siRNA, shRNA and CRISPR/Cas systems can regulate lncRNA expression in BC. Finally, lncRNAs and exosomal lncRNAs can be considered as potential diagnostic and prognostic tools in BC.

Gastrokine 2 Regulates the Antitumor Effect of JAK2/STAT3 Pathway in Gastric Cancer

GKN2 (gastrokine 2) mainly plays a regulatory role in gastric mucosal defense and cell protection mechanisms, and its role in gastric cancer has not been thoroughly elucidated. Immunohistochemistry was used to detect GKN2 and TFF1 expressions in 90 gastric cancer tissues, 48 neoplastic resection margins, and 22 normal gastric mucosa epithelia. It showed that the downregulation of GKN2 and TFF1 expressions in gastric cancer tissues was significantly different from that in adjacent normal gastric tissues and distal gastric mucosal tissues. Nevertheless, correlation analysis showed that GKN2 expression in gastric cancer tissues was independent of TFF1 expression. After overexpression of GKN2 was constructed in human gastric cancer cell line MKN28 with the Ad-GFP-GKN2 transfected, cell viability was measured by CCK-8 assay, and migration and invasion ability were analyzed by transwell migration assay and transwell invasion assay. It indicated that overexpression of GKN2 significantly reduced the viability of MKN28 and SGC7901 cells. Overexpression of GKN2 could also inhibit the migration and invasion ability in MKN28 and SGC7901 cells. In addition, upregulation of GKN2 can inactivate the JAK2/STAT3 pathway. Our data suggest that GKN2 and TFF1 play the antitumor role in gastric carcinoma, and TFF1 may not interact or cooperate with GKN2. GKN2 overexpression can inhibit the growth and metastasis by downregulating the JAK2/STAT3 pathway in gastric cancer cells.

Ginkgolide C promotes apoptosis and abrogates metastasis of colorectal carcinoma cells by targeting Wnt/β-catenin signaling pathway

Ginkgolide C (GGC), isolated from Ginkbiloba, has been reported to display various pharmacological actions, although, anti-cancer effect of GGC has been poorly understood till now. This study aimed to investigate whether GGC can exhibit anti-neoplastic effects against colon cancer cells and explore underlying mechanism. The Wnt/β-catenin signaling can regulate cell proliferation, survival, metastasis, and migration. Wnt/β-catenin signaling pathway plays important role in colorectal cancer (CRC) and acts as a potential therapeutic target. Abnormal activation of this signaling cascades has been reported in colon CRC. We found that GGC down-regulated Wnt/β-catenin signaling cascade. GGC inhibited the expression of Wnt3a, β-catenin, and β-catenin down-stream signals (Axin-1, p-GSK3β, and β-TrCP). Also, GGC suppressed the expression of Wnt/β-catenin pathway target genes including c-myc, cyclin D1, and survivin. Additionally, GGC induced apoptosis and suppressed cell proliferation, invasion, and migration. GGC down-regulated the expressions of matrix metalloproteinase (MMP)-9 and MMP-2 proteins. Moreover, silencing of β-catenin by small interfering RNA (siRNA) enhanced the GGC-induced apoptosis and inhibitory action of GGC on invasion. Overall, our results indicate that GGC can reduce proliferation and promote apoptosis in colon cancer cells through inhibition of the Wnt/β-catenin signaling pathway. Thus, GGC can serve as a potent therapeutic agent for management of colon cancer as a novel wnt signaling inhibitor.

Xanthohumol from Hop: Hope for cancer prevention and treatment

Cancer is a major public health concern due to high mortality and poor quality of life of patients. Despite the availability of advanced therapeutic interventions, most treatment modalities are not efficacious, very expensive, and cause several adverse side effects. The factors such as drug resistance, lack of specificity, and low efficacy of the cancer drugs necessitate developing alternative strategies for the prevention and treatment of this disease. Xanthohumol (XN), a prenylated chalcone present in Hop (Humulus lupulus), has been found to possess prominent activities against aging, diabetes, inflammation, microbial infection, and cancer. Thus, this manuscript thoroughly reviews the literature on the anti-cancer properties of XN and its various molecular targets. XN was found to exert its inhibitory effect on the growth and proliferation of cancer cells via modulation of multiple signaling pathways such as Akt, AMPK, ERK, IGFBP2, NF-κB, and STAT3, and also modulates various proteins such as Notch1, caspases, MMPs, Bcl-2, cyclin D1, oxidative stress markers, tumor-suppressor proteins, and miRNAs. Thus, these reports suggest that XN possesses enormous therapeutic potential against various cancers and could be potentially used as a multi-targeted anti-cancer agent with minimal adverse effects.

Blockage of the JAK/STAT3 signaling pathway in multiple myeloma by leelamine

BACKGROUND

Leelamine (LEE) is a lipophilic diterpene amine phytochemical, which can be naturally extracted from pine's bark trees. It has been extensively studied recently for its promising chemopreventive and anti-cancer effects against various cancers such as that of prostate and breast.

HYPOTHESIS

We examined the potential impact of LEE in affecting the activation of signal transducer and activator of transcription 3 (STAT3) and promoting apoptosis in human multiple myeloma (MM) cells.

METHODS

We evaluated the effect of LEE on STAT3 signaling pathway in MM cells by using Western blot analysis and reverse transcription polymerase chain reaction (RT-PCR). Thereafter, apoptosis was evaluated using cell cycle analysis and Annexin V assay.

RESULTS

We noted that LEE could attenuate the phosphorylation of STAT3 and other up-stream signaling molecules such as JAK1, JAK2, and Src activation in U266 and MM.1S cells. It also diminished STAT3 translocation into the nucleus and enhanced the expression of protein-tyrosine phosphatase epsilon (PTPε). Additionally, LEE caused cell cycle arrest and synergistically augmented the apoptotic actions of bortezomib against MM cells.

CONCLUSIONS

Our data indicates that LEE could block STAT3 signaling cascade linked to tumorigenesis and can be used in combination with approved anti-cancer agents in attenuating MM growth and survival.

Bergamottin Induces DNA Damage and Inhibits Malignant Progression in Melanoma by Modulating miR-145/Cyclin D1 Axis

Background

Melanoma is a prevalent skin cancer with the high rate of metastasis and mortality, affecting the increasing number of people worldwide. Bergamottin (BGM) is a natural furanocoumarin derived from grapefruits and presents the potential anti-cancer activity in several tumor models. However, the role of BGM in the development of melanoma remains unclear. Here, we aimed to explore the effect of BGM on the DNA damage and progression of melanoma.

Methods

The effect of BGM on the melanoma progression was analyzed by CCK-8 assays, colony formation assays, transwell assays, Annexin V-FITC Apoptosis Detection Kit, cell-cycle analysis, in vivo tumorigenicity analysis. The mechanism investigation was performed using luciferase reporter gene assays, qPCR assays, and Western blot analysis.

Results

We identified that BGM repressed cell proliferation, migration, and invasion of melanoma cells. BGM induced cell cycle arrest at the G0/G1 phase and enhanced apoptosis of melanoma cells. The DNA damage in the melanoma cells was stimulated by the BGM treatment. Meanwhile, BGM was able to up-regulate the expression of miR-145 and miR-145 targeted Cyclin D1 in the melanoma cells. Furthermore, BGM inhibited the progression of melanoma by targeting miR-145/Cyclin D1 axis in vitro. BGM attenuated the tumor growth of melanoma in vivo.

Conclusion

Thus, we conclude that BGM induces DNA damage and inhibits tumor progression in melanoma by modulating the miR-145/Cyclin D1 axis. Our finding provides new insights into the mechanism by which BGM modulates the development of melanoma. BGM may be applied as a potential anti-tumor candidate for the clinical treatment of melanoma.

Multiple Myeloma Inhibitory Activity of Plant Natural Products

A literature search on plant natural products with antimyeloma activity until the end of 2020 resulted in 92 compounds with effects on at least one human myeloma cell line. Compounds were divided in different compound classes and both their structure-activity-relationships as well as eventual correlations with the pathways described for Multiple Myeloma were discussed. Each of the major compound classes in this review (alkaloids, phenolics, terpenes) revealed interesting candidates, such as dioncophyllines, a group of naphtylisoquinoline alkaloids, which showed pronounced and selective induction of apoptosis when substituted in position 7 of the isoquinoline moiety. Interestingly, out of the phenolic compound class, two of the most noteworthy constituents belong to the relatively small subclass of xanthones, rendering this group a good starting point for possible further drug development. The class of terpenoids also provides noteworthy constituents, such as the highly oxygenated diterpenoid oridonin, which exhibited antiproliferative effects equal to those of bortezomib on RPMI8226 cells. Moreover, triterpenoids containing a lactone ring and/or quinone-like substructures, e.g., bruceantin, whitaferin A, withanolide F, celastrol, and pristimerin, displayed remarkable activity, with the latter two compounds acting as inhibitors of both NF-κB and proteasome chymotrypsin-like activity.

Paradoxical functions of long noncoding RNAs in modulating STAT3 signaling pathway in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the lethal and leading types of cancer threatening the globe with a high mortality rate. STAT3 is an oncogenic transcription factor that is aberrantly activated in several human malignancies including HCC. Many STAT3-driven genes control cell proliferation and survival, apoptotic resistance, cell cycle progression, metastasis, and chemotherapeutic resistance. STAT3 signaling is regulated by endogenous modulators such as protein tyrosine phosphatase (PTP), suppressor of cytokine signaling (SOCS), protein inhibitor of activated STAT (PIAS), and various long noncoding RNAs (lncRNAs). Interestingly, lncRNAs have been reported to exhibit oncogenic and tumor suppressor functions, and these effects are mediated through diverse molecular mechanisms including sponging of microRNAs (miRs), transcription activation/inhibition, and epigenetic modifications. In this article, we have discussed the possible role of STAT3 signaling in hepatocarcinogenesis and various mechanisms by which lncRNAs impart their oncogenic or tumor suppressive action by modulating the STAT3 pathway in HCC.

Brassinin enhances the anticancer actions of paclitaxel by targeting multiple signaling pathways in colorectal cancer cells

Brassinin (BSN), a precursor of phytoalexins, extracted from Chinese cabbage has been reported to act as a promising anti-neoplastic agent. However, the effects of BSN on colon cancer cells and its underlying mechanisms have not been fully elucidated. This study aimed at investigating the anti-neoplastic impact of BSN and its possible synergistic effect with paclitaxel on colon cancer cells. The effect of BSN on Janus-activated kinases (JAKs)/signal transducer and activator of transcription 3 (STAT3) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathways and its downstream functions was deciphered using diverse assays in colon carcinoma cells. We found that BSN displayed significant cytotoxic effect and suppressed cell proliferation on colon carcinoma cells. Additionally, it was noted that BSN modulated oncogenic gene expression and induced apoptosis through down regulating multiple oncogenic signaling cascades such as JAKs/STAT3 and PI3K/Akt/mTOR simultaneously. Besides, BSN-paclitaxel combination significantly increased cytotoxicity and induced apoptosis synergistically as compared with individual treatment of both the agents. Overall, our findings indicate that BSN may be a novel candidate for anti-colon cancer targeted therapy.

Albendazole Exhibits Anti-Neoplastic Actions against Gastric Cancer Cells by Affecting STAT3 and STAT5 Activation by Pleiotropic Mechanism(s)

Albendazole (ABZ) has been reported to display anti-tumoral actions against various maliganncies, but possible impact of ABZ on gastric cancer has not been deciphered. As aberrant phosphorylation of STAT3 and STAT5 proteins can regulate the growth and progression of gastric cancer, we postulated that ABZ may interrupt the activation of these oncogenic transcription factors. We found that ABZ exposure abrogated STAT3/5 activation, inhibited phosphorylation of Janus-activated kinases 1/2 and Src and enhanced the levels of SHP-1 protein. Silencing of SHP-1 gene by small interfering RNA (siRNA) reversed the ABZ-promoted attenuation of STAT3 as well as STAT5 activation and cellular apoptosis. In addition, these effects were noted to be driven by an augmented levels of reactive oxygen species caused by drug-induced GSH/GSSG imbalance. Thus, the data indicates that ABZ can modulate the activation of STAT3 and STAT5 by pleiotropic mechanisms in gastric cancer cells.

A Novel Role of Bergamottin in Attenuating Cancer Associated Cachexia by Diverse Molecular Mechanisms

Simple Summary

Cachexia has been generally associated with cancer causing skeletal muscle atrophy, adipose tissue atrophy, weight loss, anorexia, asthenia, and anemia, which can significantly reduce the quality of life. Our aim was to evaluate the potential effects of bergamottin on cancer-cachexia-induced muscle and fat loss. We observed a decrease in the levels of the muscle atrophy factors MuRF-1 and Atrogin-1 and increases in C/EBPα and PPARγ expression levels by bergamottin under in vitro settings. The in vivo effect of bergamottin on the inhibition of weight loss in mice and its potential inhibitory effects on cancer-induced cachexia were confirmed through analysis using tissue samples from a pancreatic cancer mouse model.

Abstract

Purpose: The potential effects of bergamotiin (BGM) on the suppression of cancer cachexia was evaluated under in vitro and in vivo conditions to investigate its possible inhibitory effects on the muscle and fat loss. Method: The differentiated C2C12 and 3T3L1 cells were treated with BGM after the induction of cancer-cachexia with pancreatic cancer conditioned media (CM). The expression levels of the various molecules involved in the differentiation and loss of muscle and fat (MuRF-1, Atrogin-1, C/EBPα, and PPARγ) were analyzed by Western blot and oil red O staining. For in vivo experiment, MIA PaCa-2 cells were injected into the mice (n = 6), and then BGM (1 mg/kg) was intraperitoneally administered to analyze muscle and adipose tissue by Hematoxylin and Eosin staining and Western blot. Result: BGM displayed a significant effect on the inhibition of muscle and fat catabolism under both in vitro and in vivo conditions. The results of the in vivo experiment revealed a remarkable suppressive effect of BGM on the weight loss in mice. Conclusions: The potential effects of BGM on the inhibition of muscle and fat catabolism in vitro and in vivo were thus confirmed. Based on the results, the impact of BGM on cancer cachexia could be possibly analyzed in the future clinical studies.

Polyphenolic molecules targeting STAT3 pathway for the treatment of cancer

Cancer is accounted as the second-highest cause of morbidity and mortality throughout the world. Numerous preclinical and clinical investigations have consistently highlighted the role of natural polyphenolic compounds against various cancers. A plethora of potential bioactive polyphenolic molecules, primarily flavonoids, phenolic acids, lignans and stilbenes, have been explored from the natural sources for their chemopreventive and chemoprotective activities. Moreover, combinations of these polyphenols with current chemotherapeutic agents have also demonstrated their strong role against both progression and resistance of malignancies. Signal transducer and activator of transcription 3 (STAT3) is a ubiquitously-expressed signaling molecule in almost all body cells. Thousands of literatures have revealed that STAT3 plays significant roles in promoting the cellular proliferation, differentiation, cell cycle progression, metastasis, angiogenesis and immunosuppression as well as chemoresistance through the regulation of its downstream target genes such as Bcl-2, Bcl-xL, cyclin D1, c-Myc and survivin. For its key role in cancer development, researchers considered STAT3 as a major target for cancer therapy that mainly focuses on abrogating the expression (activation or phosphorylation) of STAT3 in tumor cells both directly and indirectly. Polyphenolic molecules have explicated their protective actions in malignant cells via targeting STAT3 both in vitro and in vivo. In this article, we reviewed how polyphenolic compounds as well as their combinations with other chemotherapeutic drugs inhibit cancer cells by targeting STAT3 signaling pathway.

An overview of the potential anticancer properties of cardamonin

Cancer is one of the leading causes of mortality, contributing to 9.6 million deaths globally in 2018 alone. Although several cancer treatments exist, they are often associated with severe side effects and high toxicities, leaving room for significant advancements to be made in the field. In recent years, several phytochemicals from plants and natural bioresources have been extracted and tested against various human malignancies using both in vitro and in vivo preclinical model systems. Cardamonin, a chalcone extracted from the Alpinia species, is an example of a natural therapeutic agent that has anti-cancer and anti-inflammatory effects against human cancer cell lines, including breast, lung, colon, and gastric, in both in vitro culture systems as well as xenograft mouse models. Earlier, cardamonin was used as a natural medicine against stomach related issues, diarrhea, insulin resistance, nephroprotection against cisplatin treatment, vasorelaxant and antinociceptive. The compound is well-known to inhibit proliferation, migration, invasion, and induce apoptosis, through the involvement of Wnt/β-catenin, NF-κB, and PI3K/Akt pathways. The good biosafety and pharmacokinetic profiling of cardamonin satisfy it as an attractive molecule for the development of an anticancer agent. The present review has summarized the chemo-preventive ability of cardamonin as an anticancer agent against numerous human malignancies.

Role of Photoactive Phytocompounds in Photodynamic Therapy of Cancer

Cancer is one of the greatest life-threatening diseases conventionally treated using chemo- and radio-therapy. Photodynamic therapy (PDT) is a promising approach to eradicate different types of cancers. PDT requires the administration of photosensitisers (PSs) and photoactivation using a specific wavelength of light in the presence of molecular oxygen. This photoactivation exerts an anticancer effect via apoptosis, necrosis, and autophagy of cancer cells. Recently, various natural compounds that exhibit photosensitising potentials have been identified. Photoactive substances derived from medicinal plants have been found to be safe in comparison with synthetic compounds. Many articles have focused on PDT mechanisms and types of PSs, but limited attention has been paid to the phototoxic activities of phytocompounds. The reduced toxicity and side effects of natural compounds inspire the researchers to identify and use plant extracts or phytocompounds as a potent natural PS candidate for PDT. This review focusses on the importance of common photoactive groups (furanocoumarins, polyacetylenes, thiophenes, curcumins, alkaloids, and anthraquinones), their phototoxic effects, anticancer activity and use as a potent PS for an effective PDT outcome in the treatment of various cancers.

Brusatol suppresses STAT3-driven metastasis by downregulating epithelial-mesenchymal transition in hepatocellular carcinoma

Introduction

Epithelial-mesenchymal transition (EMT) is a process of transdifferentiation where epithelial cells attain mesenchymal phenotype to gain invasive properties and thus, can contribute to metastasis of tumor cells.

Objectives

The antimetastatic and antitumor efficacy of brusatol (BT) was investigated in a hepatocellular carcinoma (HCC) model.

Methods

We evaluated the action of BT on EMT process using various biological assays in HCC cell lines and its effect on tumorigenesis in an orthotopic mouse model.

Results

We found that BT treatment restored the expression of Occludin, E-cadherin (epithelial markers) while suppressing the levels of different mesenchymal markers in HCC cells and tumor tissues. Moreover, we observed a decline in the expression of transcription factors (Snail, Twist). Since the expression of these two factors can be regulated by STAT3 signaling, we deciphered the influence of BT on modulation of this pathway. BT suppressed the phosphorylation of STAT3^Y705 and STAT3 depletion using siRNA resulted in the restoration of epithelial markers. Importantly, BT (1mg/kg) reduced the tumor burden in orthotopic mouse model with a concurrent decline in lung metastasis.

Conclusions

Overall, our results demonstrate that BT interferes with STAT3 induced metastasis by altering the expression of EMT-related proteins in HCC model.

Targeting the JAK/STAT Signaling Pathway Using Phytocompounds for Cancer Prevention and Therapy

Cancer is a prevalent cause of mortality around the world. Aberrated activation of Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway promotes tumorigenesis. Natural agents, including phytochemicals, exhibit potent anticancer activities via various mechanisms. However, the therapeutic potency of phytoconstituents as inhibitors of JAK/STAT signaling against cancer has only come into focus in recent days. The current review highlights phytochemicals that can suppress the JAK/STAT pathway in order to impede cancer cell growth. Various databases, such as PubMed, ScienceDirect, Web of Science, SpringerLink, Scopus, and Google Scholar, were searched using relevant keywords. Once the authors were in agreement regarding the suitability of a study, a full-length form of the relevant article was obtained, and the information was gathered and cited. All the complete articles that were incorporated after the literature collection rejection criteria were applied were perused in-depth and material was extracted based on the importance, relevance, and advancement of the apprehending of the JAK/STAT pathway and their relation to phytochemicals. Based on the critical and comprehensive analysis of literature presented in this review, phytochemicals from diverse plant origins exert therapeutic and cancer preventive effects, at least in part, through regulation of the JAK/STAT pathway. Nevertheless, more preclinical and clinical research is necessary to completely comprehend the capability of modulating JAK/STAT signaling to achieve efficient cancer control and treatment.

Vitexin abrogates invasion and survival of hepatocellular carcinoma cells through targeting STAT3 signaling pathway

Hepatocellular carcinoma (HCC) is a major malignancy that stands second in terms of global cancer-related mortality. STAT3 has been described as a latent transcription factor that promotes tumorigenesis. This study was designed to examine the effect of vitexin on STAT3 signaling and important hallmarks of cancer. HCC cells were employed to decipher the impact of vitexin on activation of STAT3 signaling using Western blotting, EMSA, immunocytochemistry, and reporter assay. The combinational apoptotic effects of vitexin with approved anti-cancer drugs was examined by live-dead assay, and its anti-invasive potential was studied using matrigel assay. The results obtained in cell-based assays were verified using in silico analysis. Vitexin effectively inhibited sustained activation of JAK1, JAK2, Src, and STAT3 in HCC cells. Vitexin downregulated DNA binding ability, reduced the nuclear pool of STAT3, and diminished epidermal growth factor (EGF)-driven STAT3 gene expression. Interestingly, treatment with tyrosine phosphatase inhibitor altered the vitexin-induced STAT3 phosphorylation, and the attenuation of STAT3 by vitexin was found to be driven through the upregulation of PTPεC. The combinational studies indicated that vitexin can exhibit substantial apoptotic effects with doxorubicin and sorafenib. It also suppressed the CXCL12-induced cell invasion. The results of cell-based assays are supported by in silico analysis as the vitexin displayed favorable interaction with kinase domain of JAK2 protein. Overall, this study demonstrated that vitexin can act as a potential blocker of the STAT3 signaling cascade and mitigate the survival as well as invasion of HCC cells.

Imperatorin as a Promising Chemotherapeutic Agent Against Human Larynx Cancer and Rhabdomyosarcoma Cells

Naturally occurring coumarins are bioactive compounds widely used in Asian traditional medicine. They have been shown to inhibit proliferation, induce apoptosis, and/or enhance the cytotoxicity of currently used drugs against a variety of cancer cell types. The aim of our study was to examine the antiproliferative activity of different linear furanocoumarins on human rhabdomyosarcoma, lung, and larynx cancer cell lines, and dissolve their cellular mechanism of action. The coumarins were isolated from fruits of Angelica archangelica L. or Pastinaca sativa L., and separated using high-performance counter-current chromatography (HPCCC). The identity and purity of isolated compounds were confirmed by HPLC-DAD and NMR analyses. Cell viability and toxicity assessments were performed by means of methylthiazolyldiphenyl-tetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays, respectively. Induction of apoptosis and cell cycle progression were measured using flow cytometry analysis. qPCR method was applied to detect changes in gene expression. Linear furanocoumarins in a dose-dependent manner inhibited proliferation of cancer cells with diverse activity regarding compounds and cancer cell type specificity. Imperatorin (IMP) exhibited the most potent growth inhibitory effects against human rhabdomyosarcoma and larynx cancer cell lines owing to inhibition of the cell cycle progression connected with specific changes in gene expression, including CDKN1A. As there are no specific chemotherapy treatments dedicated to laryngeal squamous cell carcinoma and rhabdomyosarcoma, and IMP seems to be non-toxic for normal cells, our results could open a new direction in the search for effective anti-cancer agents.

Impact of Natural Dietary Agents on Multiple Myeloma Prevention and Treatment: Molecular Insights and Potential for Clinical Translation

Chemoprevention is based on the use of non-toxic, pharmacologically active agents to prevent tumor progression. In this regard, natural dietary agents have been described by the most recent literature as promising tools for controlling onset and progression of malignancies. Extensive research has been so far performed to shed light on the effects of natural products on tumor growth and survival, disclosing the most relevant signal transduction pathways targeted by such compounds. Overall, anti-inflammatory, anti-oxidant and cytotoxic effects of dietary agents on tumor cells are supported either by results from epidemiological or animal studies and even by clinical trials. Multiple myeloma is a hematologic malignancy characterized by abnormal proliferation of bone marrow plasma cells and subsequent hypercalcemia, renal dysfunction, anemia, or bone disease, which remains incurable despite novel emerging therapeutic strategies. Notably, increasing evidence supports the capability of dietary natural compounds to antagonize multiple myeloma growth in preclinical models of the disease, underscoring their potential as candidate anti-cancer agents. In this review, we aim at summarizing findings on the anti-tumor activity of dietary natural products, focusing on their molecular mechanisms, which include inhibition of oncogenic signal transduction pathways and/or epigenetic modulating effects, along with their potential clinical applications against multiple myeloma and its related bone disease.

Synthesis of Spin-Labelled Bergamottin: A Potent CYP3A4 Inhibitor with Antiproliferative Activity

Bergamottin (BM, 1), a component of grapefruit juice, acts as an inhibitor of some isoforms of the cytochrome P450 (CYP) enzyme, particularly CYP3A4. Herein, a new bergamottin containing a nitroxide moiety (SL-bergamottin, SL-BM, 10) was synthesized; chemically characterized, evaluated as a potential inhibitor of the CYP2C19, CYP3A4, and CYP2C9 enzymes; and compared to BM and known inhibitors such as ketoconazole (KET) (3A4), warfarin (WAR) (2C9), and ticlopidine (TIC) (2C19). The antitumor activity of the new SL-bergamottin was also investigated. Among the compounds studied, BM showed the strongest inhibition of the CYP2C9 and 2C19 enzymes. SL-BM is a more potent inhibitor of CYP3A4 than the parent compound; this finding was also supported by docking studies, suggesting that the binding positions of BM and SL-BM to the active site of CYP3A4 are very similar, but that SL-BM had a better ∆G_bind value than that of BM. The nitroxide moiety markedly increased the antitumor activity of BM toward HeLa cells and marginally increased its toxicity toward a normal cell line. In conclusion, modification of the geranyl sidechain of BM can result in new CYP3A4 enzyme inhibitors with strong antitumor effects.

Attenuation of STAT3 Signaling Cascade by Daidzin Can Enhance the Apoptotic Potential of Bortezomib against Multiple Myeloma

Daidzin (DDZ) extracted from Pueraria lobate (Fabaceae) is a widely known phytoestrogen. DDZ can display anti-cancer activities against breast and prostate cancers, but its anti-oncogenic actions in multiple myeloma (MM) cells have not been studied. The signal transducer and activator of transcription 3 (STAT3) can control key processes including proliferation, differentiation, and survival in MM cells. Here, we noted that DDZ abrogated STAT3 activation (both constitutive as well as inducible) at Tyr705 and Ser727 in MM cells. Additionally, DDZ mitigated the phosphorylation of STAT3 upstream Janus-activated kinases (JAK1/2) and c-Src kinases. Pervanadate (tyrosine phosphatase blocker) exposure altered the DDZ-induced inhibition of STAT3 activation, thus affecting the action of this phytoestrogen on apoptosis. Moreover, DDZ impeded proliferation and augmented the apoptotic effects of bortezomib (Bor) in MM cells. Overall, the data indicate that DDZ may act as a potent suppressor of STAT3 signaling cascade, and the co-treatment of DDZ and Bor could be a promising therapeutic strategy, specifically in MM.

The IκB Kinase Inhibitor ACHP Targets the STAT3 Signaling Pathway in Human Non-Small Cell Lung Carcinoma Cells

STAT3 is an oncogenic transcription factor that regulates the expression of genes which are involved in malignant transformation. Aberrant activation of STAT3 has been observed in a wide range of human malignancies and its role in negative prognosis is well-documented. In this report, we performed high-throughput virtual screening in search of STAT3 signaling inhibitors using a cheminformatics platform and identified 2-Amino-6-[2-(Cyclopropylmethoxy)-6-Hydroxyphenyl]-4-Piperidin-4-yl Nicotinonitrile (ACHP) as the inhibitor of the STAT3 signaling pathway. The predicted hit was evaluated in non-small cell lung cancer (NSCLC) cell lines for its STAT3 inhibitory activity. In vitro experiments suggested that ACHP decreased the cell viability and inhibited the phosphorylation of STAT3 on Tyr705 of NSCLC cells. In addition, ACHP imparted inhibitory activity on the constitutive activation of upstream protein tyrosine kinases, including JAK1, JAK2, and Src. ACHP decreased the nuclear translocation of STAT3 and downregulated its DNA binding ability. Apoptosis was evidenced by cleavage of caspase-3 and PARP with the subsequent decline in antiapoptotic proteins, including Bcl-2, Bcl-xl, and survivin. Overall, we report that ACHP can act as a potent STAT3 signaling inhibitor in NSCLC cell lines.

Brusatol, a Nrf2 Inhibitor Targets STAT3 Signaling Cascade in Head and Neck Squamous Cell Carcinoma

STAT3 is a latent transcription factor that plays a vital role in the transmission of extracellular signal from receptors to the nucleus. It has been regarded as a master transcription factor due to its role in the regulation of a broad spectrum of genes, which can contribute to oncogenesis. Persistent activation of STAT3 and deregulation of its signaling has been observed in various human cancers including head and neck squamous cell carcinoma (HNSCC). In the present work, we identified brusatol (BT) as a potential blocker of STAT3 signaling pathway in diverse HNSCC cells. The data from the cell-based experiments suggested that BT-induced cytotoxicity and abrogated the activation of STAT3 and that of upstream kinases such as JAK1, JAK2, and Src. It reduced the levels of nuclear STAT3 and its DNA binding ability. BT treatment increased annexin-V-positive cells, promoted procaspase-3 and PARP cleavage, and downregulated the mRNA and protein expression of diverse proteins (Bcl-2, Bcl-xl, survivin) in HNSCC cells. Taken together, brusatol can function as a promising inhibitor targeting STAT3 signaling pathway in HNSCC.

Anti-Melanogenic Effects of Bergamottin via Mitogen-Activated Protein Kinases and Protein Kinase B Signaling Pathways

In this study, we examined the inhibitory effects of bergamottin on melanogenesis in B16F10 murine melanoma cells, together with its effects on the mechanism of melanin synthesis. α-Melanocyte stimulating hormone-stimulated B16F10 cells were treated with various concentrations of bergamottin, with arbutin as a positive control. Bergamottin significantly decreased the melanin content and tyrosinase activity without showing any cytotoxicity. In addition, bergamottin treatment significantly downregulated the expression of tyrosinase-related protein-1,2 and tyrosinase by suppressing the expression of microphthalmia-associated transcription factor. The phosphorylation status of mitogen-activated protein kinases (MAPKs) and protein kinase B (AKT) was examined to determine the mechanism underlying the antimelanogenic effects of bergamottin. Bergamottin treatment increased the phosphorylation of extracellular signal-regulated kinase (ERK) and AKT, but decreased the phosphorylation of p38 and c-Jun N-terminal kinase in the B16F10 cells. Moreover, the use of PD98059 (ERK inhibitor) and LY294002 (AKT inhibitor) corroborated these findings, indicating that bergamottin inhibits melanogenesis via the MAPKase and AKT signaling pathway. Thus, bergamottin has potential for treating hyperpigmentation disorders and can be a promising chemical for skin-whitening in the cosmetic industry.

Botanical Sources, Chemistry, Analysis, and Biological Activity of Furanocoumarins of Pharmaceutical Interest

The aim of this work is to provide a critical review of plant furanocoumarins from different points of view, including their chemistry and biosynthetic pathways to their extraction, analysis, and synthesis, to the main biological activities found for these active compounds, in order to highlight their potential within pharmaceutical science. The limits and the possible improvements needed for research involving these molecules are also highlighted and discussed.

Anticancer Activity and Underlying Mechanism of Phytochemicals against Multiple Myeloma

Multiple myeloma (MM)-a common hematologic malignancy of plasma cells-accounts for substantial mortality and morbidity rates. Due to the advent of novel therapies such as immunomodulatory drugs (IMiDs), proteasome inhibitors (PIs), and monoclonal antibodies (mAbs), response rates were increased and free survival and overall survival have been elevated. However, adverse events including toxicity, neuropathy or continuous relapse are still problems. Thus, development of novel drugs which have less side effects and more effective is needed. This review aims to recapitulate the pharmacologic anti-MM mechanisms of various phytochemicals, elucidating their molecular targets. Keywords related to MM and natural products were searched in PUBMED/MEDLINE. Phytochemicals have been reported to display a variety of anti-MM activities, including apoptosis, cell cycle arrest, antiangiogenesis, and miRNA modulation. Some phytochemicals sensitize the conventional therapies such as dexamethasone. Also, there are clinical trials with phytochemicals such as agaricus, curcumin, and Neovastat regarding MM treatment. Taken together, this review elucidated and categorized the evidences that natural products and their bioactive compounds could be potent drugs in treating MM.

Arctiin is a pharmacological inhibitor of STAT3 phosphorylation at tyrosine 705 residue and potentiates bortezomib-induced apoptotic and anti-angiogenic effects in human multiple myeloma cells

BACKGROUND

Arctiin is a main component from the fruits of Arctium lappa L., that can be prescribed for cold or flu in East Asian countries; it has also been found to exert chemopreventive actions against various tumor cells.

HYPOTHESIS

In view of this evidence, we examined arctiin for its ability to trigger apoptosis and inhibit the activation of signal transducer and activator of transcription 3 (STAT3) in human multiple myeloma (MM) cells.

METHODS

We evaluated the effect of arctiin on STAT3 signaling cascades and its regulated functional responses in MM cells.

RESULTS

Arctiin effectively blocked the constitutive activation of STAT3 phosphorylation in the residue of tyrosine 705. Arctiin also abrogated the constitutive activation of Src phosphorylation and Janus-activated kinases (JAKs) 1/2. Furthermore, it was found that arctiin treatment clearly enhanced the mRNA and protein levels of protein tyrosine phosphatase ε (PTPε), and the silencing of PTPε caused a reversal of the arctiin-induced PTPε expression and the blockadge of STAT3 phosphorylation. Interestingly, arctiin could not repress IL-6-induced STAT3 activation in serum-starved U266 cells and when arctiin was incubated with a complete culture medium in RPMI 8226 and MM.1S cells. Arctiin suppressed cell proliferation, accumulated cells in the G2/M cell-cycle phase, and induced apoptosis within U266 cells, although the knockdown of PTPε prevented PARP cleavage and caspase-3 activation induced by the arctiin. In addition, arctiin exerted cytotoxicity in MM cells, but did not do so in peripheral blood mononuclear cells. Arctiin down-modulated diverse oncogenic gene products regulated by STAT3, although the induction of apoptosis by arctiin was abrogated upon transfection with pMXs-STAT3C in mouse embryonic fibroblast (MEF) cells. Arctiin also potentiated bortezomib-induced antitumor effects in U266 cells.

CONCLUSION

On the whole, our results indicate that arctiin is a potentially new inhibitor of constitutive STAT3 activation through the induction of PTPε in MM, cells and therefore has great value in treating various tumors sheltering constitutively activated STAT3.

Biomolecular Targets of Oxyprenylated Phenylpropanoids and Polyketides

Oxyprenylated secondary metabolites (e.g. phenylpropanoids and polyketides) represent a rare class of natural compounds. Over the past two decades, this group of phytochemicals has become a topic of intense research activity by several teams worldwide due to their in vitro and in vivo pharmacological activities, and to their great therapeutic and nutraceutical potential for the chemoprevention of acute and chronic diseases affecting humans. Such investigations have provided evidence that oxyprenylated secondary metabolites are able to interact with several biological targets at different levels accounting for their observed anticarcinogenic, anti-inflammatory, neuroprotective, immunomodulatory, antihypertensive, and metabolic effects. The aim of the present contribution is to provide a detailed survey of the so far reported data on the capacities of selected oxyprenylated phenylpropanoids and polyketides to trigger receptors, enzymes, and other types of cellular factors for which they exhibit a high degree of affinity and therefore evoke specific responses. With respect to the rather small amounts of these compounds available from natural sources, their chemical synthesis is also highlighted.

Pharmacological Utilization of Bergamottin, Derived from Grapefruits, in Cancer Prevention and Therapy

Cancer still remains one of the leading causes of death worldwide. In spite of significant advances in treatment options and the advent of novel targeted therapies, there still remains an unmet need for the identification of novel pharmacological agents for cancer therapy. This has led to several studies evaluating the possible application of natural agents found in vegetables, fruits, or plant-derived products that may be useful for cancer treatment. Bergamottin is a furanocoumarin derived from grapefruits and is also a well-known cytochrome P450 inhibitor. Recent studies have demonstrated potent anti-oxidative, anti-inflammatory, and anti-cancer properties of grapefruit furanocoumarin both in vitro and in vivo. The present review focuses on the potential anti-neoplastic effects of bergamottin in different tumor models and briefly describes the molecular targets affected by this agent.

Ophiopogonin D, a Steroidal Glycoside Abrogates STAT3 Signaling Cascade and Exhibits Anti-Cancer Activity by Causing GSH/GSSG Imbalance in Lung Carcinoma

Natural medicinal plants are multi-targeted in nature and their anti-cancer activities are also complex and varied, thus requiring a more systematic analysis of their modes of action. Since the activation of signal transducer and activator of transcription 3 (STAT3) is often deregulated in non-small cell lung carcinoma (NSCLC) cells and tissue specimens, its negative regulation can form the basis for identification of targeted therapy. In this report, we analyzed the possible anti-cancer effects of ophiopogonin D (OP-D) and the underlying mechanisms by which OP-D exerts its actions in NSCLC. OP-D exhibited substantial suppressive activity on STAT3 signaling and this effect was found to be mediated via oxidative stress phenomena caused by disturbance in GSH/GSSG ratio. In addition, OP-D induced apoptosis, activated caspase mediated apoptotic cascade and decreased expression of various oncogenic genes. Consistently, OP-D treatment significantly reduced NSCLC tumor growth in preclinical mouse model with via decreasing levels of p-STAT3. OP-D was also found to attenuate the expression of STAT3-regulated anti-apoptosis, cell cycle regulator, and angiogenesis biomarkers. Our findings suggest that OP-D can induce apoptosis and exert anti-tumor effects by inhibition of STAT3 signaling pathways in NSCLC.

Chemical Constituents of Thai Citrus hystrix and Their Antiausterity Activity against the PANC-1 Human Pancreatic Cancer Cell Line

Human pancreatic cancer cells have an extreme tolerance to nutrition starvation, enabling them to survive in a hypovascular tumor microenvironment. Searching for agents that preferentially inhibit cancer cell viability under nutrition starvation conditions is a novel antiausterity strategy in anticancer drug discovery. In the present study, a hexane extract of the peels of Citrus hystrix fruits showed preferential cytotoxicity against PANC-1 human pancreatic cancer cells using a nutrient-deprived medium. Phytochemical investigation of this bioactive extract led to the isolation of 10 coumarins (1-10) including a new furanocoumarin (1). The isolated compounds were tested for their preferential cytotoxic activity against three different human pancreatic cancer cell lines [PANC-1, MIA PaCa-2, and PSN-1]. Among these, bergamottin (7) was identified as the most active constituent. In real-time live imaging, 7 was found to induce cell shrinkage, membrane blebbing, and disintegration of organelles in PANC-1 cells. Bergamottin (7) was also found to inhibit PANC-1 cell migration and colony formation. Mechanistically, 7 inhibited key survival proteins in the Akt/mTOR signaling pathway. Bergamottin (7) and related compounds are potential antiausterity candidates for drug development against pancreatic cancer.

Bergamottin Suppresses Metastasis of Lung Cancer Cells through Abrogation of Diverse Oncogenic Signaling Cascades and Epithelial-to-Mesenchymal Transition

Bergamottin (BGM) is a naturally occurring furanocoumarin and is known to inhibit the growth of tumor cells. However, there is no available evidence that BGM has an inhibitory effect on cancer metastasis, specifically on the epithelial-to-mesenchymal transition (EMT) process in the malignant cells. Here we aimed to evaluate the antimetastatic potential of BGM in human lung adenocarcinoma cells. Our results demonstrate that BGM can block EMT, and observed inhibition was accompanied by downregulation of fibronectin, vimentin, N-cadherin, twist and snail expression, and upregulation of occludin and E-cadherin. Interestingly, transforming growth factor-β (TGF-β)-induced upregulation of fibronectin, vimentin, N-cadherin, twist and snail, and downregulation of occludin and E-cadherin, were abrogated by BGM treatment. Moreover, the treatment of BGM repressed TGF-β-induced cell invasive potential. BGM treatment also inhibited multiple oncogenic cascades such as PI3K/Akt/mTOR. Overall, the results demonstrate the potential antimetastatic activity of BGM against lung cancer cells.

Bergamottin Inhibits Adipogenesis in 3T3-L1 Cells and Weight Regulation in Diet-Induced Obese Mice

Obesity is a serious and increasing health problem worldwide, and the inhibition of adipogenesis is considered to be a potential therapeutic target for it. Bergamottin (BGM), a component of grapefruit juice, has been reported to regulate lipolysis. However, the physiological role of BGM in obesity has not been evaluated so far. In the present study, we investigated the effects of BGM on obesity in 3T3-L1 cells and in mice fed a high-fat diet (HFD). BGM inhibited adipogenic differentiation of 3T3-L1 cells along with a significant decrease in the lipid content by downregulating the expression of two critical adipogenic factors, CCAAT enhancer-binding protein-alpha (C/EBP[Formula: see text]) and peroxisome proliferator activated receptor-gamma (PPAR[Formula: see text]). The expressions of target proteins such as adipocyte fatty acid-binding protein (aP2), adiponectin, and resistin were also decreased by BGM. It activated AMP-activated protein kinase (AMPK) by increasing phosphorylation of AMPK and the downstream target acetyl-CoA carboxylase (ACC), indicating that BGM exerted its antiadipogenic effect through AMPK activation. In the HFD-induced obese mouse model, BGM administration significantly reduced the weight and sizes of white adipose tissue as well as the weight gain of mice fed HFD. Moreover, UCP1 and PGC1[Formula: see text] expressions, well-known as brown adipocyte marker genes, were higher in the BGM-treated HFD mice than that in the HFD-induced obese mice. This study suggests that BGM suppress adipogenesis by AMPK activation in vitro and reduces body weight in vivo.

Targeting oncogenic transcription factors by polyphenols: A novel approach for cancer therapy

Inflammation is one of the major causative factor of cancer and chronic inflammation is involved in all the major steps of cancer initiation, progression metastasis and drug resistance. The molecular mechanism of inflammation driven cancer is the complex interplay between oncogenic and tumor suppressive transcription factors which include FOXM1, NF-kB, STAT3, Wnt/β- Catenin, HIF-1α, NRF2, androgen and estrogen receptors. Several products derived from natural sources modulate the expression and activity of multiple transcription factors in various tumor models as evident from studies conducted in cell lines, pre-clinical models and clinical samples. Further combination of these natural products along with currently approved cancer therapies added an additional advantage and they considered as promising targets for prevention and treatment of inflammation and cancer. In this review we discuss the application of multi-targeting natural products by analyzing the literature and future directions for their plausible applications in drug discovery.

Bergamottin, a natural furanocoumarin abundantly present in grapefruit juice, suppresses the invasiveness of human glioma cells via inactivation of Rac1 signaling

The aim of the present study was to explore the effect of bergamottin, a natural furanocoumarin obtained from grapefruit juice, on the invasiveness of human glioma cells. The results revealed that treatment with bergamottin for 48 h significantly inhibited wound-healing migration and Matrigel invasion of human glioma cells, compared with untreated cells (P<0.05). Bergamottin treatment caused a significant decrease in the expression and secretion of matrix metalloproteinase (MMP)-9 in glioma cells compared with untreated cells (P<0.05). A Rac1-GTP pull-down assay demonstrated that bergamottin-treated glioma cells had a significantly decreased level of active Rac1-GTP compared with untreated cells (P<0.05). However, bergamottin had no significant effect on cell division cycle 42 activity. Expression of constitutively activated Rac1 almost completely restored the migration and invasion of bergamottin-treated glioma cells. In addition, bergamottin-induced downregulation of MMP-9 was prevented by exogenous activated Rac1. The results of the present study demonstrated that bergamottin exhibits anti-invasive activity in human glioma cells through the inactivation of Rac1 and downregulation of MMP-9.

ABC-transporter blockage mediated by xanthotoxin and bergapten is the major pathway for chemosensitization of multidrug-resistant cancer cells

Furanocoumarins derived from herbal and citrus extracts can act as antibacterial, antioxidant, immunomodulator, apoptotic, and selective anticancer agents, prompting a biological investigation to determine and predict their clinical therapeutic significance. Here, the cell cytotoxic effects of bergapten and xanthotoxin were analyzed alone and in combination with standard chemotherapeutics on three multidrug resistant cells and their nonresistant parental counterparts. The furanocoumarins modulatory effects on MDR1, BCRP, and MRP pump expression and function were investigated. Although quantitative real time PCR demonstrated that the MDR transcript level changes in a time dependent manner, flow cytometric analyses using fluorescent-labeled antibodies have indicated that bergapten and xanthotoxin had no significant effect on the protein levels. FACS analyses indicated that these prominent anticancer agents significantly blocked MDR1, BCRP, and MRP transporter function. Maximum furanocoumarin-mediated pump activity blockage in the MDR-resistant cells was quantified as 87% of normal and consequently, chemotherapeutic accumulation increased up to 2.7-fold and cytotoxicity tension increased 104-fold. MDR1 efflux kinetics also revealed that the maximum velocity and the pump affinity to daunorubicin were uncompetitively decreased. We conclude that bergapten and xanthotoxin are cytotoxic agents capable of preventing daunorubicin, mitoxantrone, and cisplatin binding to ABC-transporters and subsequently inhibiting their efflux out of cells and they may be a potential combination therapy for malignant cancers.

Characterization and Purification of Bergamottin from Citrus grandis (L.) Osbeck cv. Yongjiazaoxiangyou and Its Antiproliferative Activity and Effect on Glucose Consumption in HepG2 cells

Bergamottin is a natural furanocoumarin compound with weak polarity. Characterization and quantification of bergamottin were carried out in different fruit tissues of various citrus cultivars. Among the four citrus tissues tested, i.e., flavedo, albedo, segment membrane (SM), and juice sacs (JS) in eight citrus cultivars, the highest bergamottin content was found in the flavedo of Citrus grandis (L.) Osbeck cv. Yongjiazaoxiangyou (YJZXY, 666.54 μg·g⁻¹ DW). A combination of silica gel column chromatography and high-speed counter-current chromatography (HSCCC) was established to efficiently purify bergamottin from the flavedo of YJZXY. Bergamottin showed significant antiproliferative activity on three cancer cell lines, i.e., human liver cancer HepG2, promyelocytic leukemia HL-60, and gastric cancer BGC-823 cells, which showed a marked inhibition effect on these cell lines in a dose-dependent manner. In addition, bergamottin significantly increased glucose consumption in HepG2 cells also in a dose-dependent manner, which is the first report of its potential in anti-diabetes applications.